The present invention is in the field of polymers containing basic groups and ion-exchange groups. The invention relates in particular to methods for lateral chain modification of aryl main chain polymers with aromatic ketones and aldehydes containing basic nitrogen (N) groups and to the polymers made according to the methods.
A) Polymers Modified with Basic N
There are still relatively few basic N-modified polymers on the market, the most important of which are mentioned below:
poly(4-vinyl pyridine), poly-2-vinyl pyridine) and copolymers.
These two polymers are commercially available, also as block copolymers with polystyrene. They are used for example as pre-stages for anion exchange membranes (Reiner, Ledjeff1, Gudernatsch, Krumbholz2) or complexed with Schiff""s bases containing cobalt for selective oxygen permeation3. The drawback with this class of polymer is the tertiary Cxe2x80x94H-bond in the polymer main chain, which is susceptible to oxidation.
Polybenzimidazols
Polybenzimidazols are a class of polymers which have considerable chemical and mechanical stability. Many types of polybenzimidazols (fully and partly aromatic) have already been synthesised and examined4. However, only a few types are produced commercially, of which the most important is the polymer PBI (poly[(2,2-m-phenylene)-5,5xe2x80x2-bibenzimidazol) produced by Celanese under the commercial name CELAZOLE. This polymer is used, inter alia, in the form of low-flammability textiles5 for the Fire Brigade. The drawbacks with this polymer are that it is difficult to dissolve in organic solvents and so has poor working properties. In addition, this polymer is very expensive.
Polyethylene imine
Polyethylene imine is used in organic chemistry and biochemistry as a precipitating agent for proteins6. The advantage of this polymer is that by virtue of its highly hydrophilic nature (1 N on 2 C), it is water soluble and therefore, in its pure form, will not form any resistant membranes. Furthermore, by virtue of its purely aliphatic structure, it is not very chemically stable.
B) Anion Exchange Polymers and Membranes
The commercial anion exchange polymers and membranes can be divided into two main categories:
anion exchange polymers which are produced by reaction of chlorinated7 or bromomethylated8 polymers with tertiary amines. The drawback with this reaction is the carcinogenic nature of the halomethylation reaction and the lack of chemical stability of the aromatic-CH2xe2x80x94NR3+grouping.
anion exchange polymers produced by the alkylation of tertiary N, for example of poly(vinyl pyridine)1,2,9 with halogen alkanes1,2. The disadvantage with this reaction is that only very few commercial polymers with tertiary N are available (see above) and thus the range of membrane properties to be achieved is limited. The drawback with poly(vinyl pyridine)s is limited chemical stability (see above).
C) Cation Exchange Polymers Sulphonated in the Lateral Group
There are very few commercial polymers and membranes of this type. The most important are:
nafion10 
This polymer has a perfluoralkyl main chain and a perfluorether lateral chain at the end of which hangs a sulphonic acid group. This polymer is used in applications which require great chemical membrane stability, for example, in membrane fuel cells11. The disadvantage of this polymer is its high price ($800/sq.m) and complicated production process10.
poly-X 200012 
This polymer consists of a poly(phenylene) main chain and an aryl lateral chain. The precise name of this polymer is poly(oxy-1,4-phenylene-carbonyl-1,4-phenylene). This polymer is sulphonated12 only at the end of the lateral chain. Reportedly12, this polymer in the sulphonated form has good proton conductivity levels even at temperatures in excess of 100xc2x0 C. at which the proton conductivity of sulphonated poly(ether ether ketone) (PEEK) drops markedly. This property could be brought out by a better association of the sulphonic acid groups in the poly-X 2000, since the sulphonic acid groups are in the lateral chain in the case of the poly-X 2000xe2x80x94in the sulphonated PEEK, the sulphonic acid groups are in the main chain and consequently, on account of the rigidity of the PEEK main chain, they associate less readily. A drawback with this polymer is its poorer thermal stability compared with sulphonated PEEK12 and the fact that it is not commercially available.
The invention is directed to:
(1) A method for the lateral chain modification of engineering aryl main chain polymers with arylene-containing basic N-groups by the addition of aromatic ketones and aldehydes containing tertiary basic N-groups (such as for example tertiary amine, pyridine, pyramidine, and triazine) to the metallized polymer.
(2) Lateral chain modified polymers obtainable by the methods of the invention, whereby the lateral chain contains at least one aromatic group which carries a tertiary basic N.
(3) A method for quaternizing the tertiary N of the modified polymers obtainable according to the invention with halogen alkanes in order thus to incorporate anion exchanger groups into the lateral chain modified polymer.
(4) Engineering aryl main chain polymers carrying in the lateral chain anion exchanger functions and obtainable by the methods of the invention.
(5) A method for the lateral chain modification of engineering main chain polymers with arylene-containing basic N groups by the following reaction of aromatic carboxylic acid Arxe2x80x94COORxe2x80x2 containing tertiary basic N groups (such as for example tertiary amine, pyridine, pyramidine, and triazine) with the metallized polymer Pxe2x80x94Me: 
(6) Lateral chain modified polymers obtained by the methods of the invention in which the side chain contains at least one aromatic group which carries a tertiary basic N.
(7) A method of quaternizing the tertiary N of the modified polymers obtained by the methods of the invention with halogen alkanes to incorporate anion exchanger groups into the lateral chain modified polymer.
(8) Engineering aryl main chain polymers carrying in the lateral chain anion exchanger functions obtainable by the methods of the invention.
(9) A method for the lateral chain modification of engineering aryl main chain polymers with aromatic groups containing sulphonic acid radicals by the following sequence of reactions:
(9a) Reaction of the aromatic carboxylic acid ester Arxe2x80x94COORxe2x80x2 or carboxylic acid halide Arxe2x80x94COHal with the metallized polymer Pxe2x80x94Me: 
(9b) Controlled electrophilic sulphonation of the lateral group with sulphuric acid SO3/P(O)(OR)3, CISO3H, or other sulfonating reagent. The lateral group is in this case so selected that its reactivity for sulphonation is substantially higher than the reactivity of the polymer main chain for sulphonation.
(10) Engineering aryl main chain polymers which only carry sulphonic acid functions in the lateral chain, obtainable by the methods of the invention.
(11) Membranes of the polymers obtainable according to the present invention, in which the membranes may be unvulcanised or covalently cross-linked.
(12) A method of producing acid-based blends/acid-based blend membranes from the basic polymers of the invention with polymers containing sulphonic acid, phosphonic acid or carboxyl groups.
(13) A method of producing acid-based blends/acid-based blend membranes from the basic polymers of the invention with the polymer of the invention containing sulphonic acid groups.
(14) Acid-based blends/acid-based blend membranes obtainable by the methods of the invention, whereby the blends/blend membranes may in addition be covalently cross-linked.
(15) Use of the ion exchange polymers of the invention in the form of membranes in membrane processes such as in polymer electrolyte membrane fuel cells (PEFC), direct methanol fuel cells (DMFC) and electrodialysis.
(16) Use of hydrophilic polymers of the invention containing the basic N in the lateral group in the form of membranes in dialysis and in reversed osmosis, nanofiltration, diffusion dialysis, gas permeation, pervaporation and perstraction.
For many applications in membrane technology (reversal osmosis, nanofiltration, micro- and ultrafiltration, electrodialysis, diffusion dialysis, membrane electrolysis, membrane fuel cells), hydrophilic or chemically stable polymers containing ion exchange groups are needed. However, these polymers are only commercially available in limited amounts. Even today, in some cases vinyl polymers with limited chemical stability are still being employed in the above-mentioned applications. Furthermore, the range of the properties of these commercial polymers is not very great.
As a result of this invention, aryl main chain polymers and membranes which are modified with basic nitrogen in the lateral group have become available. These polymers and membranes are hydrophilic and have very good thermal and mechanical stability. Furthermore, this invention provides chemically stable cation and anion exchange membranes which additionally, by reason of the presence of the ion exchange groups in the lateral chain, display a greater degree of freedom for forming ion exchange group associates than if the ion exchange groups were present in the polymer main chain.
In particular, the invention is directed to a method for producing engineering aryl main chain polymers having aryl-containing basic N-groups having the general formula 
wherein P is a polymer with the repeating units 
wherein R3 is hydrogen, alkyl or aryl,
and said units R1 and/or R2 are linked by at least one group selected from 
R7 is an aromatic group containing tertiary basic N,
R8 is hydrogen, alkyl or aryl, which optionally contains tertiary basic N,
X is hydrogen or an alkyl group,
comprising
a) reacting metallized polymer Pxe2x80x94Me, wherein Me is Li or Na, with an aromatic ketone or aldehyde containing tertiary basic N-groups and having the general formula 
xe2x80x83to give an intermediate product of formula: 
(b) protonating with water or etherifying with an alkyl halide.
The invention is also directed to a method for producing an engineering aryl main chain polymer having aryl-containing basic N-groups, comprising reacting a metallized polymer Pxe2x80x94Me described above with an aromatic carboxylic acid derivative having tertiary basic N-groups of formula 
wherein R10 is an aromatic group containing tertiary basic N-groups and
Y is a halogen or xe2x80x94Oxe2x80x94R11, wherein R11 is an alkyl group or an aryl group.
The invention is also directed to a method for producing an engineering aryl main chain polymers having aryl-containing quaternary N-groups, comprising quarternizing the engineering aryl main chain polymers having aryl-containing basic N-groups with one or more halogen monoalkanes.
The invention is also directed to a method for producing engineering aryl main chain polymers having aryl-containing quaternary N-groups, comprising quarternizing and covalently cross-linking the engineering aryl main chain polymers having aryl-containing basic N-groups with a mixture of halogen mono- and halogen dialkanes
The invention is also directed to a method for producing engineering aryl main chain polymers having aromatic sulphone acid groups, comprising reacting an engineering aryl main chain polymer having aryl-containing basic N-groups with a sulphonating agent.
The invention is also directed to a method for producing a polysulphone having sulphonated aromatic side chains and having the general formula 
comprising metallizing polysulphone PSU Udel(copyright) with lithium to give, for example, a lithiated polymer of the formula 
and reacting with an aromatic carboxylic acid derivative of the formula 
wherein Z is a halogen, and
reacting the reaction-product with sulphuric acid.
The invention is also directed to a method for producing anion exchange polymers, comprising reacting metallized polymers Pxe2x80x94Me described above with diaromatic ketones having tertiary N-groups and then oxidizing the polymer in dilute mineral acid in solution or dispersion by the use of an oxidation agent. A particularly preferred oxidizing agent is air in an acid solution.
The invention is also directed to a method for producing polymer membranes, comprising dissolving the polymers of the invention in a dipolar aprotic solvent, applying the polymer solution to a backing as a thin layer, and removal of the solvent, e.g. by evaporation. Examples of such backings include a glass plate, a woven fabric or a fleece.
The invention is also directed to a method for producing acid-base blend membranes, comprising mixing the polymers of the invention with polymers in acid or salt form containing sulphonate, phosphonate or carboxylate groups in a dipolar aprotic solvent, applying the polymer solution to a backing as a thin layer, and removing the solvent.
The invention also relates to methods of using the membranes obtained according to the invention in membrane processes, particularly in polymer electrolyte membrane fuel cells, direct methanol fuel cells, diffusion dialysis and electrodialysis. Particular uses include dialysis, reversal osmosis, nanofiltration, gas permeation, pervaporation and perstraction.